Operational circuitry for pipe organs



April 3, 1968 H. A BURTON 3,379,085

OPERATIONAL CIRCUITRY FOR PIPEORGANS Filed Aug. 18, 1965 INVENTOR.HOWARD A. BURTON ATTORNEY United States Patent 0 3,379,085 OPERATIONALCIRCUITRY FOR PIPE ORGANS Howard A. Burton, 3045 3rd Ave.,

Marion, Iowa 52302 Filed Aug. 18, 1965, Ser. No. 480,699 9 Claims. (Cl.84-337) ABSTRACT OF THE DISCLOSURE A solid state electronic circuit foruse in the key and stop action circuits of pipe organs to control thevalves operating the organ pipes.

This invention relates to operational circuitry for pipe organs and moreparticularly relates to solid state circuits for use in the key and stopaction circuits of direct electric and electropneumatic pipe organs.

Until very recent times, the prior art relating to direct electric andelectropneumatic pipe organs has employed the use of mechanical andelectropneumatic relays in the organ key and stop action circuits. Forexample, in a typical direct electric organ, a wire wound coil with aniron core magnet is used to activate a direct electric magnet whichopens the valve to a given organ pipe when the key circuit is closed bydepressing the organ key for that particular note. Similarly, in atypical electropneumatic pipe organ, the iron core magnet actuates anair valve and the pipe is operated by the use of air pressure. Similarcircuitry has been employed for the stop action. With thesearrangements, the organ keyboards have thus consisted of a group orgroups of electric switches for the making or breaking of the circuitsto the coils or magnets.

With the invention of solid state semi-conductors, such devices haverecently been used in organ key circuits. For example, a solid state keycircuit is disclosed in U.S. Patent No. 3,138,052, issued June 23, 1964,to M. M. Wick and entitled, Organ Key Circuit. However, the circuitsdisclosed in this patent and other existing circuits have certaininherent disadvantages which affect their reliability and performance,even though such circuits are much superior to the circuits which employmechanical and electropneumatic relays.

It is therefore a principal object of my invention to provide improvedcircuits for the operation of organ keys and stop actions, whichcircuits utilize solid state semiconductors to accomplish all therequirements applicable to electropneumatic or direct electric organsand associated equipment.

Another object of my invention is to provide an improved solid statecircuit for use in key and stop action organ circuits, which circuitemploys a single diode and coil combination that blocks sneak or phantomcircuits through which current could flow in reverse to actuate some ofthe chest magnets and possibly cause damage to the transistors used inthe circuits.

A further object of my invention is to provide an improved solid statecircuit for use in organ key and stop action circuits in which thecollector of each transistor is grounded to a common negative pole ofthe power supply, thus, providing for the use of a metal mounting panelas a common ground and as a heat sink for the transistors to dissipatethe heat normally developed within the transistors.

A still further object of my invention is to provide an improved solidstate circuit for use in organs in which a fixed resistor is connectedto the base of each transistor at the positive pole of the power supply,thus providing a continuous positive bias to the point of cutoff andpreventing the flow of current within the transistor until the circuitis closed. A circuit constructed according to the 3,379,085 PatentedApr. 23, 1968 principles of my invention will thus prevent thepossibility of damage to the transistor when the circuit is open or inan unkeyed state.

It is another object of my invention to provide an improved solid statecircuit for use in both key and stop action circuits for organs, whichcircuit is extremely reliable, relatively inexpensive, and which is soconstructed that the tuning of the organ is greatly simplified,

These and other objects and advantages of my invention will be readilyapparent from consideration of the following description taken inconnection with the accompanying drawing which shows a preferredembodiment of my invention and in which:

FIG. 1 is a schematic wiring diagram for one key or note of an organmanual or pedal board and illustrates the principles of my invention fora transistorized key circuit in connection with a straight chest,showing the use of a single diode in series with the chest magnets;

FIG. 2 is a schematic wiring diagram illustrating the principles of myinvention as applied to a transistorized stop action circuit;

FIG. 3 is a schematic wiring diagram showing the transistorized stopaction circuit of FIG. 2, combined with the basic transistorized keycircuit of FIG. 1; and

FIG. 4 is a schematic wiring diagram showing the principles of myinvention as applied to a key circuit for an augmented pedal or manual.

It will be understood that the key circuits illustrated in FIGS. 1 and 3of the drawing are for a single key which activates the same note ineach chest or rank of organ pipes, and each chest or rank is controlledby a stop through an individual circuit as shown in FIG. 2. Referringnow to the drawing, and particularly to FIG. 1, a key contact 10, whichis actuated by depressing a key on the organ, is connected to the groundor negative side of a suitable D-C power supply supplying, for example,10 volts of direct current power. The other side of key contact 10 isconnected to the base 12 of a suitable power transistor 11, such as a2N555 power transistor. A fixed carton resistor 13 is also connectedbetween the positive side of the power supply and the base 12 of thetransistor 11 in order to bias the transistor to a positive polarity atits base. The collector 14 of the transistor 11 is connected to theground or negative pole of the power supply, as shown, and the emitter16 is connected to four parallel branches which represent four typicalchest circuits each containing a series diode 18 which has a lowresistance path from its cathode to its anode. It will be understoodthat the number of parallel circuits will depend upon the number ofchests or ranks of pipes in the particular organ in which the circuit isused. Although four such parallel branches are indicated, for purposesof simplicity only one of said branches is shown in connection with asingle electropneumatic or direct electric chest magnet 19, it beingunderstood that the other branches would be similarly connected. It willbe further understood by those skilled in the art that each chestcircuit will contain a plurality of chest magnets 19, eg sixty-one ormore. Each magnet 19 controls a diiferent pipe or note in that chest,and the same note in each chest will be controlled by one of thesixty-one key contacts 10. Each chest magnet 19 consists of a coil 20and a core 22, the coil 20 of each magnet being connected directly to acommon return wire 24, one such common being provided for each chest ofpipes. It will be understood that all the chest magnets 19 in each chestof pipes will be con nected to a'common wire 24.

Since in the typical organ a stop is provided to control each rank orchest of pipes, I have illustrated a common and well known stop actioncircuit in connection with my novel key circuit. Such a circuit usuallycontain a relay 26 and a stop action switch 28 as shown. The relay 26has a single throw switch 30, one side of which is connected to thecommon wire 24, the other side of switct 30 being connected to thepositive pole of the power supply. The switch 30 is actuated by a coil32, one side of which is also connected to the positive pole of thepower supply, the other side being connected through the stop actionswitch 28 to the ground or negative pole of the power supply.

Thus, it will be evident that when the key contact is closed, no notewill speak unless the stop action switch 28 for at least one of thechests of pipes is closed to energize armature 32 and close relay switch30 in that stop action circuit. Moreover, when the key contact 10 isclosed, the notes will speak in all of the chests of pipes whose stopaction switches 28 have been close-d.

The positive bias of transistor 11 provided by resistor 13 will preventcurrent from flowing from the collector 14 to the emitter 16 therebypreventing damage to the transistor 11 when the key circuit is open orin an unkeyed state. However, when the key contact 10 is closed, thepositive bias will be removed from the base 12 of the transistor 11allowing current to flow from the negative side of the power supplythrough the collector 14 to the emitter 16. If the stop action switch 28is closed in one or more of the stop action circuits, the relay 26 inthat circuit will be activated to close relay switch 30 and complete thecircuit between the common wire 24 and the positive side of the powersupply. Current will then flow through diode 18 and through the chestmagnet 19, the coil 20 of which is wired to the common wire 24, andthrough relay switch 30 to the positive side of the power supply. Withchest magnet 19 thus activated, a valve will be opened to sound theorgan pipe in the chest which has been activated by closing of stopaction switch 28.

Because of the reverse current characteristic that is always presentwithin any transistor, there are at least three normal conditions whichcan occur during which the transistor experiences self-degeneration inthe form of runaway or avalanche-like response. These conditions are:(1) change in polarity; (2) voltage spike; and (3) excessive heat. Mynovel circuits avoid these conditions and thus improve the life of thetransistors used and provide for extremely high reliability.

sWhen the key contact 10 is released and the circuit open, acounter-electromotive force from the coil 20 of the chest magnet returnsa voltage of reverse polarity to the circuit which can cause damage tothe transistor 11 or activate other key circuits in the organ. Thishighly undesirable but normal condition is prevented from causing harmin each key circuit by diode 18 which has a high resistance reversecurrent flow, thus preventing anything but a negligible and harmlesscurrent to return through the circuit. Moreover, as previouslyindicated, when the key contact 10 is open, the resistor 13 biases thetransistor 11 toa positive polarity at base 12 which prevents currentfrom flowing through the collector 14 to the emitter 16 and therebyprevents damage to transistor 11 while the circuit is in unkeyed state.

Since the collector 14 of each transistor 11 is at the negative polarityof the power supply, this permits the transistors for all the keycircuits to be mounted on a metal panel which will serve as a heat sink,thereby dissipating heat generated Within the transistors and improvingtheir life and the reliability of the key circuits. This is particularlyimportant due to the inherent temperature sensitivity of transistors.

Also, because of my novel circuit arrangement, if the diode 18 shouldfail, the only effect will be that one note or pipe in a single chestwill speak. In prior art solid state circuits known to me, failure of adiode will permit that note in all of the chests to speak, an obviouslyundesirable condition particularly when the number of chests of pipes islarge. Since only a single note will speak if a diode should fail in mycircuit, this diode can be quickly detected and replaced. 1

Moreover, in the key circuit illustrated in FIG. 1, all of the chests orranks of pipes are tied to the common wire 24. This permits control ofthat note in all of the chests through the use of a single relay switchwhereas prior art circuits have required the use of multiple switches ora stack switch, one switch for each note in each chest. This, of course,adds to the cost and complexity of the circuitry and decreases itsreliability.

Referring now to FIG. 2, the principles of my invention are illustratedin connection with a solid state transistorized stop action circuit, andin FIG. 3 the circuit of FIG. 2 is shown in combination with the keycircuit of FIG. 1. As shown, the stop action switch 28 is connected tothe negative side of the power supply and to the base 34 of a powertransistor 35 of any suitable design or type similar to that used in thecircuit of FIG. 1. The collector 36 of the transistor 35 is connected tothe ground or negative side of the power supply, and the emitter 38 isconnected in series with a diode 40 which has a low resistance path fromits cathode to its anode. The diode 40 is then connected in series withthe coil 32 of the relay 26 which is connected to the positive side ofthe power supply. Coil 32 actuates the relay switch 30 which is in thecircuit between the common wire 24 and the positive side of the voltagesupply. Similar to the key circuit of FIG. 1, a resistor 42 between thebase 34 of the transistor 35 and to the positive side of the powersupply, will bias the transistor 35 to a positive polarity at the base34 and prevent damage to the transistor even when the circuit is open.Also, the collector 36 is at a negative polarity which permits themounting of all the stop action transistors on a metal panel that servesas a heat sink.

The stop action circuit of FIG. 2 operates in a similar manner to thecircuit of FIG. 1 to control the pipes in a particular chest. Thus, whenthe stop action switch 28 is closed, the positive bias is removed fromthe base 34 of the transistor 35 and current flows from the negativeside of the voltage supply through the collector 36 to the emitter 38and through diode 40 to energize the coil 32 of the relay 26. Thiscloses the relay switch 30 to complete the circuit between the commonwire 24 and the positive side of the power supply. Thus, the pipes inthat chest will speak when the keys are depressed to close the keycircuits.

Diode 40 has a high resistance reverse current flow similar ot diode 18which prevents transient voltages from returning to the emitter 38 ofthe transistor 35 when the circuit is open.

Referring now to FIG. 4, the principles of my invention are illustratedas applied to a key circuit for an augmented pedal or manual, whicharrangement is built in many organs and which permits the borrowing of anote for a given stop.

To illustrate, a single chest of pipes which will permit the notes inthat chest to speak at a two-foot pitch, as well as either a four or aneight-foot pitch, will consist of eighty-five pipes. The manual, forexample, will consist of sixty-one keys or notes, but to permit eachnote to speak at the various pitches, it is necessary to borrow notes,as is well known to those skilled in the organ construction art. Thealternative is to provide a separate pipe for each note and each pipe,which is obviously expensive and space-wasting.

In FIG. 4, reference numeral 10 represents the key contact for a singlenote, as before, and transistor 11 is connected as in FIG. 1 and FIG. 3with the base 12 biased to a positive polarity by resistor 13 and withthe collector 14 connected to ground. The emitter 16 of transistor 11 isconnected to a plurality of parallel circuits which represent thecircuits for a single note at three different pitches in a single chestof pipes.

In each of these parallel circuits is a diode 18 which has a lowresistance path from its cathode to its anode. Each diode 18 isconnected in series with a chest magnet 19 which in turn is connected toa common wire 44 that is connected to the positive side of the powersupply. In each parallel circuit, also in series with diode 18, is aswitch 46. Switches 46 are preferably each part of a separate relay andtherefore actuated by the relay coil when it is energized. The relay maybe actuated by closing of a stop action switch in a circuit such' asthat shown in either FIG. 1 or 2. It will be understood that for eachpitch there will be sixty-one switches 46, one of each note or key, andall sixty-one switches 46 for that pitch will be closed by a single stopaction switch. To accomplish this, a suitable multiple contact gang orstack switch can be used as is well known to those skilled in the art.

Thus, the basic principles of my invention can be applied to both keyand stop action circuits, and these two circuits utilized together willprovide extremely high reliability in the operation of either directelectric or electropneumatic organs. My novel circuitry relieves thenormally heavy current on the chest magnets thereby minimizing theburning out of the key contacts. The circuits are extremely simple butyet are so designed that the transistors used will be completelyprotected from reverse currents which might damage them. Also, thedesign of the circuitry permits the mounting of the transistors on ametal panel which can serve as an excellent heat sink to dissipate theheat normally generated in the transistors, particularly the collectors.The system, although simple, eliminates phantom circuits which mightotherwise actuate chest magnets in unkeyed circuits or cause damage tothe transistors. Moreover, by biasing the transistors to a positivepolarity at the base immediately upon opening of the circuits, there .isno flow of current within the transistors until the circuits are closedand the bias removed.

It will be obvious to those skilled in the art that the basic principlesof my novel circuit have a wide variety of applications and that variousrevisions and modifications can be made therein without departing fromthe spirit and scope of my invention. It is my intention, however, thatany such revisions or modifications which are obvious to those skilledin the art will be included within the scope of the following claims.

I claim:

1. A circuit for controlling the operation of pipes in an organ having adirect current power supply and a chest magnet, including a coil,controlling the action of each organ pipe, said circuit comprising apower transsistor having a base, an emitter, and a collector, saidcollector being connected to the negative side of the power supply, aswitch operable by the organist and connected at one side of thenegative side of the power supply and at the other side to the base ofsaid transistor, a diode having its cathode connected to said emitterand its anode connected to said magnet coil, a resistor connectedbetween the base of said transistor and the positive side of said powersupply to bias said transistor to a positive polarity when said switchis open, and means operable by the organist to open and close saidcircuit.

2. The circuit of claim 1 in which said switch is a key switch and thereare a plurality of chest magnet coils in parallel circuits, each of saidparallel circuits containing one of said diodes in series with eachmagnet coil, a common wire connects the positive sides of said coils,and said means includes a switch in each of said parallel circuitswhereby each parallel circuit may be closed independently of the other.

3. A circuit for controlling the operation of pipes in an organ having adirect current power supply and a chest magnet, including a coil,controlling the action of each organ pipe, said circuit comprising apower transistor having a base, an emitter and a collector, saidcollector being connected to the negative side of the power supply, akey switch operable by the organist and connected at one side to thenegative side of the power supply and at the other side to the base ofsaid transistor, a diode having its cathode connected to said emitterand its anode connected to said magnet coil, means for opening andclosin the circuit between said magnet coil and the positive side ofsaid power supply, and a resistor connected be tween the base of saidtransistor and the positive side of said power supply to bias saidtransistor to a positive polarity when said switch is open.

4. The circuit of claim 3 in which said means includes a secondtransistor having a base, an emitter, and a collector connected to thenegative side of the power supply, a second stop switch operable by theorganist and connected at one side to the negative side, of the powersupply and at the other side to the base of said second transistor, arelay including a coil and a switch and having the switch connectedbetween said magnet coil and the positive side of said power supply, anda second diode having its cathode connected to the emitter of saidsecond transistor and its anode connected to the coil of said relay, theother side of the relay coil being connected to the positive side of thepower supply, and a second resistor connected between the base of saidsecond transistor and the positive side of said power supply to biassaid second .transistor to a positive polarity when said second switchis open.

5. The circuit of claim 3 in which there are a plurality of chest magnetcoils in parallel circuits, each of said parallel circuits containingone of said diodes in series with each magnet coil, a common wireconnects the other sides of said coils, and said means is connectedbetween said common wire and the positive side of the power supply.

6. The circuit of claim 4 in which there are a plurality of key switchcircuits controlling a plurality of organ pipes, each key switchcontrolling a pipe for the same note in a chest of pipes, a plurality ofstop action circuits one for each chest of pipes, the chest magnet coilsin each chest are in parallel circuits, each of said parallel circuitscontaining one of said first named diodes in series with each chestmagnet coil, a common wire connects the other sides of said coils ineach chest, and the relay switch in each stop action circuit connectedbetween the common wire for that chest and the positive side of thepower supply.

7. A circuit for a pipe organ having a direct current power supply and achest magnet, including a coil, con trolling the action of the organpipe, said circuit comprising a power transistor having a base, anemitter, and a collector, said collector being connected to the negativeside of the power supply, a stop action switch operable by the organistand connected at one side to the negative side of the power supply andat the other side to the base of said transistor, a relay including acoil and a switch and having the switch connected between said magnetcoil and the positive side of the power supply, a diode having itscathode connected to said emitter and its anode connected to the coil ofsaid relay, the other side of the relay coil being connected to thepositive side of the power supply, a resistor connected between the baseof said transistor and the positive side of said power supply to biassaid transistor to a positive polarity when said stop switch is open,and means for opening and closing the circuit between said magnet coiland the negative side of said power supply.

8. The circuit of claim 7 in which there are a plurality of chest magnetcoils in parallel circuits, a common wire connects to one side of eachof said magnet coils, and said relay switch is connected between saidcommon wire and the positive side of said power supply.

9. In a circuit for controlling the operation of a pipe organ having adirect current power supply, a chest magnet controlling the action ofthe organ pipe, and a manually operated switch opened and closed by theorganist; a power transistor having a base connected to the negativeside of said power supply through said 7 switch, a collector-connecteddirectly to the negative side of the power supply, and an emitter; adiode having a low resistance pathfrom its cathode to its anode andhaving its cathode connected to the emitter of said transistor and itsanode connected to said chest magnet; and a resistor connected betweenthe base of said transistor and the positive side of said power supplyto bias said transistor to a positive polarity when said switch is open.

'8 References Cited UNITED STATES PATENTS 6/1964 Wick -Q. 84-337 9/1964Gibbs et a1. 307-885

